1. Field of the Invention
The present invention relates to a roller bearing oil feed device and in particular relates to a roller bearing oil feed device that is suitable for use with a splitter section of a manual transmission for a vehicle.
2. Description of the Background
FIG. 5 shows a splitter section (primary gear-change section) that is positioned most on the input side of a manual transmission for a vehicle. This transmission comprises an input shaft 1 whereby engine drive is transmitted and a main shaft 3 within the input shaft 1 whereby one end thereof is freely relatively rotatably and coaxially supported by means of needle bearings 2. The input shaft 1 is freely rotatably supported in a transmission case 4 by means of bearings 5. A counter shaft 6 is arranged in parallel with the input shaft 1 and main shaft 3 below the input shaft 1 and main shaft 3. The counter shaft 6 is also freely rotatably supported by means of bearings 7 on the transmission case 4.
An input gear 8 is freely rotatably supported on the outer peripheral side of the input shaft 1 by means of needle bearings 8a. A splitter gear 10 constituting a first main gear is freely rotatably supported by means of the roller bearing 9 on the outer peripheral side positioned most on the input side (left-hand side in the Figure) in the axial direction of the main shaft 3. An input counter gear 18 and splitter counter gear 19 that are normally in mesh are respectively fixed to the input gear 8 and splitter gear 10 on the counter shaft 6.
A splitter transmission mechanism 11 is provided between the input gear 8 and the splitter gear 10. The splitter transmission mechanism 11 comprises a hub 12 provided on the input shaft 1, a sleeve 13 that is normally in mesh and freely slidable in the axial direction at the outer peripheral section of the hub 12, dog gears 14 and 15 that are respectively fixed to the input gear 8 and splitter gear 10 and synchro cones 16 and 17 that are provided between the hub 12 and the dog gears 14 and 15. Splines are provided in the inner peripheral section of the sleeve 13 and the outer peripheral section of the hub 12, synchro cones 16 and 17 and dog gears 14 and 15 such that the sleeve 13 and hub 12 and the synchro cones 16 and 17 and dog gears 14 and 15 can be meshed. An identical first gear change mechanism 20 (only part shown in the Figure) is also provided behind the splitter gear 10 (right-hand side in the Figure).
When the sleeve 13 is in the position shown in the Figure, the splitter is in a neutral position (N); when the sleeve 13 moves forwardly (left-hand side in the Figure) from this position, the sleeve 13 meshes with the synchro cone 16 and the dog gear 14 with the result that the splitter assumes the “high position” (H). Contrariwise, when the sleeve 13 moves backwards (right-hand side in the Figure), the sleeve 13 meshes with the synchro cone 17 and the dog gear 15 with the result that the splitter assumes the “low position” (L). In this way, the splitter can be changed over between the three positions: H-N-L. During driving of the vehicle, the splitter initially splits the drive force of the input shaft 1 to H or L (selects H or L). There are a large number of main gears and counter gears behind the splitter, outside the Figure, and behind these in turn there is arranged a range gear for changing over H-L. This transmission is a multi-stage transmission with a larger number of stages than normal (for example 12 stages or 16 stages etc).
However, because the splitter gear 10 is a helical gear or the splitter gear 10 becomes the drive side or the driven side depending on the different H or L position, or because of the application of force in the thrust direction to the splitter gear when the splitter gear change mechanism 11 and the first gear change mechanism 20 perform gear change, the roller bearing 9 that supports the splitter gear 10 must be capable of supporting both radial load and thrust load.
Accordingly, as the roller bearing 9, conical roller bearings consisting of two rows of cones arranged symmetrically as shown in the Figure are employed. Specifically, the roller bearing 9 chiefly comprises an outer ring 21 that is fitted and fixed by pressing in etc into the inner peripheral section of the splitter gear 10, an inner ring 22 that is fitted and fixed by pressing in etc into the outer peripheral section of the main shaft 3 and rolling elements 23 comprising a plurality of conical rollers arranged in each case in the circumferential direction in a plurality of rows (two in this case) and in the axial direction between the outer ring 21 and inner ring 22. The inner ring 22 is equally divided in the axial direction for each row of the rolling elements 23 (in this case it is divided into two) and a ring-shaped spacer 24 is interposed between the inner rings 22, 22 at the position of this division, in the space in the axial direction. The spacer 24 is loosely fitted in the outer peripheral section of the main shaft 3. The dimensions in the axial direction of the positions of these inner rings 22, 22 and spacer 24 are specified beforehand by means of a stop member 25 and a larger diameter step 26 of the main shaft 3; the clearance in the axial direction of the inner rings 22, 22 and the spacer 24 in this position is adjusted by suitably selecting a plurality of spacers 24 having different widths in the axial direction. The outer ring 21 is restrained in the axial direction by means of a pair of stop rings 27 and each row of rolling elements 23 is held by means of a respective holder 28.
Also, an oil feed device as detailed below is provided in order to lubricate the contact interface on the inside of the roller bearing 9, in particular between one rolling element 23 and its fellow (inner ring 22 or outer ring 21). That is, on the inside of the main shaft 3, there is provided a branch hole 30 constituting an oil feed hole extending to the outside in the radial direction from the main oil hole 29 inside the main shaft 3, at the position where the main oil hole 29 is provided along the central portion thereof and of the spacer 24 in the axial direction. This spacer 24 is formed of channel-shaped cross-section open on the radially inner side facing the outlet of the branch hole 30. In other words, a circumferential groove 31 communicating with the outlet of the branch hole 30 and that extends along the entire circumference thereof is provided in the spacer 24. Also, a plurality (in this case, four) of oil feed holes 32 are provided in the circumferential direction, passing through the bottom face of the circumferential groove 31 (face positioned on the most radially outward side) and through the outer circumferential surface of the spacer 24.
Lubricating oil supplied from an oil pump, not shown, as shown by the arrows in the Figure, flows through the main oil hole 29 forwards in the axial direction of the main shaft 3, is branched to the branch hole 30, temporarily accumulated in the circumferential groove 31 of the spacer 24 and is then discharged in the radially outwards direction from the oil feed holes 32 by centrifugal force produced by the rotation, thereby lubricating the inside of the roller bearing 9.
However, with such a construction, when the sleeve 33 of the first gear-change mechanism 20 meshes with the dog gear 34 that is fixed behind the splitter gear 10, the input shaft 1 and the splitter gear 10 rotate in synchronization (i.e. they do not rotate relatively). Consequently, the outer ring 21 and inner rings 22 of the roller bearing 9 then rotate in synchronization. Consequently, in a condition in which the rolling elements 23 do not roll, the condition in which radial load and thrust load are applied to the contacting locations of the outer ring 21 and inner rings 22 and rolling elements 23 continues. Thus, in a condition in which the rolling elements 23 are not rolling, since movement of the contacting locations of the rolling elements 23 and the outer ring 21 and inner rings 22 is also not taking place, the lubricating oil at the contact interface tends to be insufficient and so-called fretting wear tends to occur.
In such a situation, with the oil feed device described above, oil discharged from the oil feed holes 32 of the spacer 24 tends to fly radially straight outwards due to the centrifugal force, slipping through between the rolling elements 23 of each row until it collides with the intermediate space in the axial direction of the inner peripheral surface of the outer ring 21 and tend to flow towards both ends in the axial direction along the inner peripheral surface of the outer ring 21. Consequently, notwithstanding that a comparatively large quantity of oil is supplied to the contacting locations of the rolling elements 23 and the outer ring 21, it is difficult to achieve a supply of oil to the contacting locations of the rolling elements 23 and the inner rings 22 and fretting wear therefore tends to be produced at these contacting locations. Also, since the oil feed holes 32 of the spacer 24 are provided with a prescribed separation in the circumferential direction, there is a possibility that, between oil feed holes 32 that are adjacent in the circumferential direction, oil will not sufficiently penetrate to the contacting locations at positions which are more remote in the axial direction; this too tends to cause fretting wear on the side of the inner rings.